Zylon® Body Armor Controversy: Safety, Liability, and Fiber Degradation

Introduction: History of Body Armor

Body armor has a long history of trial-and-error development, and throughout history designers of armor have struggled to keep pace with those who created weapons designed to pierce it. Somewhat amusingly, the first recorded armor was made of light and flexible materials not entirely unlike those used today, if overwhelmingly more low-tech. Both body armor and shields were made from animal skins. However, advances in technology led to wooden and metal shields and various forms of body protection. Metal breastplates appeared in very early history, and by the Middle Ages full suits of armor were created that sheathed every part of the wearer's body in protective metal. While crossbows and longbows that could penetrate armor posed a danger, it was the coming of firearms that finally made metal armor completely obsolete. Bullets could easily pierce even thick metal shells.

Meanwhile, in Japan, soft body armor was being developed that might be considered a direct ancestor of today's bulletproof vest. Using silk — which was significantly stronger than most other natural fibers — medieval Japanese armor makers could create tough garments that helped turn blades. So when the American military began researching the possibility of creating body armor capable of stopping bullets, silk became one of the primary candidates. There was some limited success with this approach, and silk body armor could stop low-velocity bullets. However, it offered nothing against more advanced high-velocity ammunition. Many other forms of body armor were proposed, but none proved particularly feasible.

The next meaningful development came during World War II with the invention of the "flak jacket," which was comprised of a ballistic nylon and provided some protection against flak and other munitions fragments, though it was not particularly effective against pistols and rifles. Flak jackets certainly saved lives during the war, but they were not a viable option for peacetime law enforcement officers.

In the 1960s, new forms of synthetic fibers made the manufacture of effective body armor a reality. After extensive research by the National Institute of Justice's Bureau of Standards, it was discovered that DuPont's material called Kevlar would work remarkably well as a ballistic fiber. "Ironically, the fabric was originally intended to replace steel belting in vehicle tires." (NIJ) According to Lester Shubin, who managed the project: "The Army notified me that DuPont had a new fabric to replace steel belting for high-speed tires. When I saw it, I realized it might be a great improvement over nylon for personal armor... and I took a piece of Kevlar to a gun range. The bullets didn't go through." (NIJ)

Kevlar thus became the standard for body armor for many years. Much of the development work was done by government agencies such as the FBI, the Secret Service, and the National Bureau of Standards. The government also funded private contractors such as The Aerospace Corporation and the MITRE Corporation, and the U.S. Army became involved in research as well. To some degree, this intense study of Kevlar's properties differed from the work that went into Zylon® as a material, which was explored primarily by independent companies. Kevlar was tested against a wide range of bullets, and the vest design was finalized through a process that included medical testing to determine what level of protection was necessary during regular police duty — partly because of concerns about blunt trauma inflicted by non-penetrating bullets.

Like Zylon® today, researchers found that Kevlar degraded under less-than-ideal circumstances. Sunlight, cleaning agents including bleach, repeated washing, and moisture were all identified as potential threats to the integrity of the body armor. One important fact to remember from this era is that this early armor "was designed to ensure a 95% probability of survival after being hit with a .38 caliber bullet at a velocity of 800 ft/s. Furthermore, the probability of requiring surgery if hit by a projectile was to be 10% or less." (NIJ) In other words, in the era when Kevlar was the standard, a 5% fatality rate while wearing the jacket was considered acceptable. This is significant context when one approaches the story of how a single bulletproof vest failed after almost a thousand from the same company had succeeded — a 0.1% fault rate.

Kevlar eventually gave way to Zylon® as the preferred standard because Zylon® appeared to be not only much stronger, but also far lighter, making the vests more comfortable to wear. Many officers chose to leave their vests behind while on patrol simply because they downplayed the risk and found the vests too uncomfortable. By making vests lighter, less constricting, and better fitted, the number of officer casualties could potentially be reduced.

How Bulletproof Vests Work and Current Fiber Types

Understanding how bulletproof vests work is relevant to understanding the controversy surrounding Zylon®. Bulletproof vests, whether made with Kevlar or Zylon®, are formed from a weave of fibers. When a bullet strikes the vest, those fibers absorb some of the impact and transfer the energy to nearby fibers, spreading it throughout the vest. Each layer of ballistic fabric presents a further barrier to the bullet and absorbs more of its energy, causing the bullet to become increasingly deformed and slow-moving. By distributing the force of the blow across a larger area, it is possible to dissipate the energy necessary to penetrate the body, though severe bruising may still occur. Unfortunately, without an impractically large number of layers — which would make vests rigid and unwearable on a regular basis — it is only possible to protect against low- and medium-energy handgun fire. Rifle fire, Teflon-coated bullets, and other extreme variables may be sufficient to pierce even the best cutting-edge body armor. This is also important to keep in mind when evaluating claims that a vest has "failed," since there is always a chance that the threat was too severe for even a vest in perfect condition. For example, the officer injured in the recent vest failure still has the bullet lodged in his body, so it is impossible to determine at this point whether the bullet had some kind of special external coating or had been specifically modified to defeat body armor.

The fiber types currently used in creating body armor include: Kevlar, a man-made organic fiber available in several varieties; Spectra fiber, a polyethylene fiber with a vaguely gel-like appearance; TWARON, which uses a patented Microfilament technology and is exceptionally light; and Dyneema, which is also remarkably light and offers high energy absorption. Zylon®, considered the strongest fiber known to man, until recently remained a favorite for personal body armor.

The Zylon® Controversy: The Incident and Industry Response

The change was precipitated by a single failure that led to the unveiling of a growing body of research regarding the potential failures of Zylon® fiber. As the National Border Patrol Council reported: "It began with a single gunshot. Last summer, an undercover police officer stepped out of a van in Pennsylvania to make a drug bust and was shot in the abdomen. The bullet penetrated the front panel of his body armor. The officer survived, but the damage — to him and to an industry that exists specifically to protect law enforcement — was done."

Almost immediately, a great outcry arose among those who had purchased the same type of vest that Officer Limbacher was wearing at the time of the shooting. It has been estimated that approximately 200,000 police officers own and wear Second Chance Zylon® vests of the same type. The outrage over one near-fatal shooting persists despite the fact that Second Chance vests had "recorded more than 900 'saves' — instances when medical personnel have confirmed that its vests protected an officer from serious injury or death — [and] the Ultima and Ultimax vests [in question] account for 37 of those saves." (National Border Patrol Council)

Today the controversy concerns whether Zylon® should continue to be used in bulletproof vests at all, and also whether Second Chance should be held responsible for the full financial costs of replacing more than 200,000 vests currently in use (at a cost of between $500 and $1,000 each — an amount that would certainly bankrupt the company). It is toward answering this controversy, or at least understanding it, that this paper is directed.

Conclusion

As this detailed review of the associated literature makes clear, the controversy surrounding Zylon® is very tangled with contradictions and uncertainties. It appears that no thoroughly scientific review has been conducted that takes into account all the different manufacturing processes that may transform Zylon®, nor aging under both ideal conditions and conditions of slight misuse. More research on this topic is definitely necessary, but in the meantime it would certainly be advisable for companies to discontinue manufacturing Zylon® body armor in favor of one of the many alternatives available.

Nonetheless, a little perspective is necessary. Only one vest has ever failed, while thousands have successfully saved the lives of those wearing them. Likewise, the founder of Second Chance has reportedly allowed himself to be shot while wearing a bulletproof vest on approximately 200 separate occasions. All of this adds up to a very low failure rate, especially given the natural inconsistencies one might expect with something as dangerous as gunfire. Whether or not Zylon® is the best fiber for the job, it has served its purpose in the past and may not deserve to be fully discredited.

Other options are available, of course, though many are unattractive on other grounds. Kevlar is heavy but has far less of a tendency to degenerate over time. Other vest materials face similar constraints, and achieving the goal of "lighter but stronger" may still require years of additional testing. In the meantime, one would suggest that police agencies move to replace their Zylon®-based vests by whatever means necessary, or at least order and install the special ballistic patches that Second Chance is distributing free of charge.

Suing Second Chance does not seem like the most valid approach to this situation, because Second Chance has so far been the only American body armor manufacturer to act responsibly by recalling the potentially faulty Zylon® vests and trying to protect officers from what could be a fatal design flaw. This kind of honesty should be rewarded as much as possible — even if that means paying a reduced amount for new vests — especially considering that vests less than a year old are offered at only about 20% of the original cost, an amount that may not even cover replacement expenses. While new grants may be needed to cover these replacements, to some degree they should be funded by reserves already set aside to replace vests at the end of their normal five-year service life.

Suing the remaining armor corporations that insist on continuing to use Zylon® might be more appropriate, though it would not necessarily succeed, given the widespread obfuscation of data that appears to predominate in this matter. If one is unwilling to work with Second Chance after this episode, it remains difficult to identify another manufacturer who is more ethically approachable on this issue.

Overall, the conclusions must be as follows: Zylon® may or may not be safe in the long run — though it has functioned well in the short run — and to be on the safe side, conversion to other types of ballistic vests should be made as soon as possible. However, no real blame should attach to Second Chance, which does not appear to have had any serious foreknowledge of this problem and has acted more responsibly than any of its competitors in addressing it.